The present invention relates to a method for feeding and clamping thread in a thread winding device for textile machines. The thread winding device has a U-shaped bobbin frame with a first and a second centering disks for receiving bobbins. The centering disks are mounted to free ends of the legs of the U-shaped bobbin frame such that inwardly oriented faces of the centering disks are facing each other and are rotatable about a centering axis extending through the first and the second centering disks. At least a first centering disk is tiltable about two axis that are perpendicular to one another and to the centering axis and at least the second centering disk is slidable against the force of a spring in an outward direction relative to the U-shaped frame. The bobbin inserted into the U-shaped bobbin frame is axially moved in an outward direction together with the second centering disk so that between the first centering disk and the bobbin a slot is created into which the beginning of the thread is introduced and clamped by returning the bobbin and the second centering disk into their starting position.
The described method is usually carried out by hand in known apparatuses of the aforementioned kind.
The manual feeding of the beginning of the thread, for example, in a double-twisting machine, is started by introducing the beginning of the thread into a notch of a specially prepared bobbin or, as mentioned above, is introduced into a space between the end of the bobbin and the face of the centering disk facing the bobbin. The operating personnel opens the bobbin frame by hand, moves the bobbin to one side and inserts the thread into the clamping slot between the bobbin and the centering disk. Auxiliary devices for such manually performed methods are not necessary.
With the apparatus known from DE-OS 23 12 609 the beginning of the thread is changed between the centering disk and the bobbin by hand. With the known apparatus no auxiliary devices are therefore required. However, an automatic feeding of the beginning of the thread is impossible.
A thread winding device with the aforementioned features is known and, for example, described in DE-PS 27 11 024. In this known device, the beginning of the thread is moved by a gripping arm into the vicinity of a bobbin that is provided with holes. A suction line is provided within the bobbin frame and air is sucked via openings provided at the face of the centering disk from the interior of the bobbin. Due to the stream of air which is flowing from the outside through the holes into the interior of the bobbin, the beginning of the thread is sucked into the interior and held in place so that, when rotating the bobbin, the following thread portions may be wound up.
The described device has the disadvantage that a number of complicated auxiliary devices must be provided at the thread winding device and, furthermore, that the bobbins must be provided with holes.
A device for clamping the beginning of the thread within the area of the centering disks that are disposed at a bobbin frame and receive a bobbin, is described in DE-PS 25 36 477 whereby one of the centering disks is provided with a groove extending in the circumferential direction. The groove is provided with paired thread clamps. These thread clamps are in the form of notches that extend towards the bottom of the groove within the sidewalls of the groove in the direction of rotation of the centering disk and also against the direction of rotation. The inwardly directed side walls within the area of each individual clamp pair (notches) are provided with undercut catches that are oriented in the direction of rotation of the centering disk. With this device, the beginning of the thread is fastened directly to the centering disk and in this case further auxiliary devices are required at the centering disk.
The problem to be solved by the present invention lies in the fact that, on the one hand, the imitation of the manually performed introduction of the beginning of the thread to the respective thread winding device results in an extraordinarily complicated feeding device and, on the other hand, the known devices for an automatic thread feeding and subsequent clamping require complicated auxiliary devices at the thread winding device itself.
It is therefore an object of the present invention to improve the aforementioned methods for feeding and clamping threads in a thread winding device so that an automatic feeding and clamping of the beginning of the thread is possible without the need for complicated auxiliary devices at the thread winding device. This means that the thread winding device should not be provided with any further components which are not commonly present in known thread winding devices.